A Comparison Of Methods To Identify Pre-existing Cognitive Impairment In Patients Presenting For Coronary Artery Bypass Graft Surgery
Lis Evered, Brendan Silbert, David Scott
Centre for Anaesthesia and Cognitive Function, Department of Anaesthesia, St. Vincent’s Hospital, Melbourne, Australia
Purpose of Study
The ability of the clinician to identify the existence of cognitive impairment prior to medical or surgical intervention is important because prior cognitive status may be a determinant of Post Operative Cognitive Dysfunction (POCD). The statistical methodology used to define cognitive impairment is important because different methods may result in differing outcomes. We compared the incidence of pre-existing cognitive impairment when two common statistical methods were used to analyse the results of cognitive testing.
Method
The cognitive test results of 349 patients scheduled for elective coronary surgery were drawn from the ANTIPODES (AustraliaN Trial Investigating Post-Operative cognitive Deficit, early Extubation and Survival) Trial. The Institutional Ethics Committee approved the study and written informed consent was obtained from all patients. These results were then analysed using two recent methods. One method was used to define Age Associated Cognitive Decline (AACD) (Busse et al), the other to define Pre-existing Cognitive Deficit (PCD) (Hogue et al). One hundred and seventy control participants without cardiovascular disease were drawn from two previous studies for the latter analysis.
Results
The two methods (AACD and PCD) yielded a similar prevalence of pre-existing cognitive impairment in patients presenting for CABG surgery when applied to the ANTIPODES data (28.4% vs 35.0%). There was substantial agreement between these two methods (kappa=0.678, 95% CI: 0.623 - 0.733..
Conclusion
The inference from this study is that baseline cognitive impairment and age-associated cognitive decline are related entities, possibly reflecting similar pathophysiology. If the present finding extends to the many different forms of cognitive impairment previously described, this may lead to a simplification of analysis of this challenging problem. This may, in turn, lead to more effective research and improved understanding of the aetiology of pre-existing cognitive impairment.
References
1. Busse, A., J. Bischkopf, et al. (2003). "Mild cognitive impairment: prevalence and incidence according to different diagnostic criteria. Results of the Leipzig Longitudinal Study of the Aged (LEILA75+)." Br J Psychiatry 182: 449-54.
2. Hogue, C. W., Jr., T. Hershey, et al. (2006). "Preexisting cognitive impairment in women before cardiac surgery and its relationship with C-reactive protein concentrations." Anesth Analg 102(6): 1602-8.
Time of Presentation
1530
